Abrading apparatus



May 3, 1938. w. I KEEFER 2,116,153

ABRADING AFPARATUS. y

Fi 1ed sept. 2,' 1937 s sheets-sheet 1 55,43 SL/WM SIMM/1f- Ma'y 3,1938. w. L. KEEFER ABRADING APPARATUS Filed Sept. 2, 1937 5 Sheets-Sheet2 May 3, 1938. l w. l... KEA-:FER A 2,115,153 ABRADING APPARATUS Filedsept. e, 1957 s shets-sheet s Patentedl May 3, 1938 `I UNITED STATESPATENT ()FFICE Pangborn lCorporation, corporation of MarylandHagerstown, Md., a

Application September 2, 1937, Serial No. 162,214

26 Claims.

'Ihe present invention relatesto abrading ap paratus, and moreparticularly to apparatus known in the trade as blast cleaning machinesembodying means for projecting a stream ofabrasive in thel form of sandor steel abrasive wherein the abrasive is admitted at low velocity4 15over the inner ends. of the blades and is continuously accelerated tothe blade tips or whether they are wheels. embodying batter blades wherethe entire abrading velocity is imparted to the abrasive by a singleinstantaneous impact therewith. Y

Although the slidervtype machines in commercial use today represent agreat advance in the art over the machines heretofore in use they do notpossess all oi' the operating characteristics desired and fallconsiderably short of the ideal machine which would pick the abrasive upwithout shock and gradually Vmove it out to the periphery of the rotorwithout sliding it and then discharge it without wearing influence uponany part of the machine.

It is accordingly a primary object of this invention to provide anabrasiveA throwing wheel which does not employ any blades whatsoever andmore nearly approaches the ideal abrading apparatus than anythingheretofore proposed.

It is another object to devise a centrifugal abrading machine whereinthe abrasive is admitted near the axis of rotation, moves outwardly withsubstantially no propelling influence and then is released from thewheel substantially at the peripheral speed thereof without having abatting or other impacting action applied thereto. It is a furtherimportant object to design a wheelfor mechanically vthrowing abrasivewhich employs no blades whatsoever, retains a prede- .ermlned quantityofabrasive in the wheel at all times and discharges a predetermined`quantity at each rotation of-'the wheel and imparts a high abradingvelocity tothe abrasive.

' My invention also aims to provide an abrasive and feeding andpropelling assembly that may be used in combination with centrifugalbladed rotors for imparting directional control thereto.

Further objects of the invention will become apparent as theaccompanying specication proceeds in connection with the annexeddrawingsand from the appended claims.

In the drawings:

Figure 1 is a longitudinal sectional view of lan apparatus embodying theinvention.

,Figure 2-is a view looking from the right hand side of the machineshown in Figure l and parts have been 'broken away in order to moreclearly show the structure involved.

Figure 3 is a sectional view taken on the line 10 3 3 o f Figure 2showing the parts as .they appear when viewed in the direction of thearrows.

Figure 4 isa fragmental sectional view of a part of wheel shown inFigure 1 and illustrates one of the abrasive discharge openings. 15

Figure l5 is an elevational view of the feed chamber of the machine ofFigure 1, and illustrates the abrasive dellector.

Figure 6 is a. longitudinal sectional view similar to Figure l butillustrates a modiiled form of the invention.

Figure 7 is an elevational view looking from the right handside o fFigure 6 and parts have been broken away in order to more clearly showthe structure involved.

Figure 8 is a fragmental sectional view of the s machine shown inFigures 6 and 'l and illustrates the rotatable disc employed to deflectlor dislodge the abrasive from the inner surface of the wheel.

Figure 9 is a longitudinal sectional view Vthrough a further modifiedform oi' wheell also forming part of the invention.

Figure 10 is a partial elevational view of the machine shown in Figure 9and illustrates it as 35 it appears when viewed from the right hand sideof that ligure.

Figure 11 is a fragmental partial sectional view of machine shown inFigures 9 and 10 and shows the deecting members. 4-0

Figure 12 is a face view of a bladed rotor-embodying the abrasivepropelling mechanism of the invention.

Figure 13 is 'a longitudinal sectional view through the wheel shown inFigure ,12, and in this form the defiecting disc has been onlydiagrammatically illustrated. p

Figure 14 is an enlarged sectional view of the feeding mechanismemployed inthe machine of Figures 12 and 13 andl illustrates the mannerin 50 which the abrasive is introduced into the abrasive chamber anddischarged therefrom.

With continued reference to the .drawinga whereinlike referencecharacters have been employed throughout the several views thereof tomanner.

designate like parts, and with particular reference to Figures 1 to 5,inclusive, the machine broadly comprises a hollow rotatable member uponwhose inner surface the abrasive is centrifugally built up and the layerof abrasive is automatically discharged from the member at apredetermined point in rotation by means of a defiector which directlyengages the layer of abrasive deposited within said member.

The hollow member just referred to includes a head I0, which is mountedon a shaft II. The latter is journaled for rotation in any suitable Asseen in Figure 1, head I is hollowed out from one side and is providedwith an abrasive accelerating groove I2 at its periphery which mergeswith a radial face I3 of the rotor. Head IIJ is also provided with aflanged portion Il in which a plurality of abrasive discharge openingsI5 are provided.

In order to provide for wear oi the parts and make it possible toreplace certain parts of the machine Without replacing the entire rotor,a wear bushing I1 is disposed in each opening I5 and as seen in Figures1 and 4, each wear bushing I1 is provided with a portion extending intoopening I5 and is provided with an inclined rear wall I8 for a purposethat will presently appear.

A disc 2| is preferably secured to the end of the rotor for preventinginadvertent escape of abrasive,.but it may be omitted if desired.

'I'he abrasive may be admitted to the interior of the rotor in anysuitable manner, but I preferably employ a generally cone shaped member22 having a funnel portion 23 and which is mounted on a shaft 24. Shaft24 is journaled in a bearing 25 provided on a bracket 26 and the latteris secured to a stationary base 21.

Feed chamber 22 is accordingly mounted for rocking movement about theaxis of rotation of the rotor and it is provided with a handle 28 formanipulating it into its adjusted position. A set screw 29 is threadedinto bracket 26 for locking shaft 24 in its proper adjusted position.

Assuming that shaft II is driven by any suitable prime mover at a speedof approximately 2500 revolutions per minute, and abrasive is admittedto spout 23, it will travel at relatively low velocity until it strikesthe mass of abrasive in the abrasive acceleration groove I2, where itwill be picked up and rapidly attain the peripheral speed of the rotor.In view of the fact that when the Wheel is in operation groove I2 isfilled with abrasive, theaccelerating action imparted to the abrasive istaken by the abrasive itself that is accumulated in the groove, andaccordingly Wear of the acceleration groove walls is minimized.

Assuming that the wheel is rotating as just de-I scribed, the abrasivewill fill up groove I2 and then spill over onto the internal surface 3|of the rotor. The parts are so designed, and rotor surface 3| is ofsuilicient Width so that as the abrasive builds up it will assume theform of a cone with its inner surface inclined at an angle equal to theangle of repose of the particular abrasive, and during normal operationwill not spill into openings I5 unless it is acted upon by thedefiector, which will now be described.

One form of defiector means that may be used to dislodge abrasive at apredetermined point in the revolution of the rotor, is shown in Figures3 and 5, and it consists of acomparatively thin' blade 33 made from anysuitable heat resistant material, such as tungsten alloy steel. y

Deflector blade 33 may be stationarily supported in any desired mannerbut in the present instance I have shown it as being supported by a pairof bosses 34 on member 22 by means of a pair of screws 35.

Deector 33 is curved as seen in Figure 2, and its outer edge lies inclose proximity to the inner surface of the rotor, with the result thatwhen the wheel is rotated the layer of abrasive lying on surface 3| willbe continuously acted upon by the defiector and deflected into openingsI5. f

Referring to Figure 3, with the Wheel rotating in the directionindicated by the arrow, an abrasive particle is indicated at 38 as justcontacting blade 33. This particle, prior to engagement thereof with thedefiector possessed a velocity Vr or a velocity equal to the peripheralspeed of the rotor.

Upon engagement of the particle with defiector 33, it assumes a velocityhaving an axial component Vd and the two combined give a resultantvelocity Vx. Therefore, there is continuously deposited on the innersurface 3| a layer of abrasive and this layer of abrasive is beingcontinuously discharged from the wheel at one point by reason ofdefiector 33 engaging it and causing it to be pushed axially intoregistry with the discharge openings. Y

In view of the fact that the abrasive lying centrifugally on surface 3|is rotating atthe peripheral speed of the wheel, and as this speed isselected to correspond to the desired abrasive discharge speed, it isunnecessary to impart a blade action upon the abrasive as it is spilledthrough opening I5 in order to impart an abrading velocity thereto. WallI8 of opening I5 is accordingly inclined as shown in Figure 4 in orderto avoid an impelling influence being given to the abrasive as it passesthrough opening I5. However, if desired, the combination of the rimdischarge and blade action may be used, and in a succeeding form of theinvention I have shown a machine of just this character.

In view of the fact that the point of discharge of the abrasive isdependent upon the angular position of defiector 33, the wheel may becaused to fire in any direction by loosening screw 29 and rocking thefeed chamber 22 in the proper direction to cause the machine todischarge in the desired direction. As a matter of fact, if it isdesired to have the machine discharge upwardly the feed chamber may belocated in the position shown in the drawings, but the defiector may besecured thereto at a point 180 degrees removed from the location shownin order to make the Wheel fire upwardly rather than downwardly. Ifafter the Wheel is in use it is found that the spray angle or the widthof the centrifugal blast is too narrow, the defiector may be movedcloser to the Wheel so as to deflect'a greater depth of abrasive foreach revolution, or the defiector may be longer so as to deflect agreater body of abrasive or a flange may be provided on the defiector todislodge a greater quantity of abrasive. To this end member 33 may beadjustably mounted on chamber 22 or any other stationary part of themachine.

If desired, however, two deectors may be placed in series at differentangular points so as to increase the width of the abrasive spray angle.

.Although I have shown a particular feed chamber for introducing theabrasive in the rotor, it is to be understood that if desired variousother forms of abrasive admitting means may be used. For instance,abrasive may be admitted at the center of a pair of grooved rotatingdiscs and be l to lock it in place.

allowed to trickle -outwardly thereover and gradually4 accelerated.

Taking up the formrof invention illustrated in Figures 6, 7 and 8, themajor differences between this device and the first described form oithe invention reside in the use of a wheel having passages for graduallyaccelerating abrasive as it moves outwardly and also, a rotatable 4discwhich is employed to deflect the abrasive at a predetermined point inrotation. In this form of the invention a rotor 4D is mounted on shaft4I and is provided with a pair of abrasive accelerating flanges and 43,an abrasive acceleration groove 44 and an abrasive supporting or depositsurface 45.

In this form of the invention feed chamber 46 is similar to thatpreviously described with the exception that it provides a pair ofannular grooves 41 and 48 which cooperate with flanges 42 and 43 ofrotor 40 to dene a tortuous passage. Thereforel when the abrasiveintroduced in chamber 46 rstencounter's ilange 42 it is partiallyaccelerated, fills up to the angle of repose and 'spills off the edgeinto groove 41 where it is deilected onto flange 43. Flange 43 beingfurther. from the axis of rotation is rotating at a greater peripheralspeed than ange 42, the abrasive accordingly receives furtheracceleratitm when'it strikes this viiange. 'I'he abrasive then spillsoif flange 43 into the acceleration groove, which, being located stillfurther from the axis of rotation further accelerates the abrasive.-

The feed chamber is mounted on a shaft i5 as before, which is journaledin a bracket 5l carried by a base 52. An operating handle 53 is employedto rock the feed chamber into vthe proper angular position and the setscrew 54 is employed In this form of the invention a disc 55 cooperateswith the rotor to spill the abrasive over the side edge of the rotor andit is journaled in a bearing 51 carried by an arm 58 which, as shown, isan integral part of the feed chamber, with the result that the directionof discharge may be controlled by rocking the feed chamber.

friction of the abrasive upon the wheel is scient to Acause it toundergo independent rotation.

Disc 56 may also, ii desired, be adjustably supported so as to disposeits axis at any suitable inclination tothe axis of the wheel. l

fBy reason of the fact that the peripheral speed of disc 55 issubstantially equal to the peripheral speed oi' rotor lill, it isapparent that it will undergo a minimum abrading action duringoperation, and at the same time smoothly spills the abrasive over theside or discharge edge 55 of the rotor.

Although l have illustrated disc 5t as lying at a predetermined anglewith respect to the axis of rotation of rotor du, it is to be understoodthat vthis angle may be increased or the disc axis inclined so as todispose the disc in other directions for discharging the. abrasive fromthe wheel, depending upon the particular work being handled, theabrasive used, and other inuential factors.

It is accordingly seen that with this forni oi l 'of inventiondescribed, the abrasive discharge isdiscontinuous in the sense that itis successively discharged through openings l5. If desired surrigidlycarried by shaft di. f

ltace 45 and/or edge 59 may be formed in a separate removable andreplaceable wear element'.

It will be understood that a disc deiiector like that used in the formor the-invention illustrated l in Figures 6, 7 and 8 may be used insteadoi' the '.deector 33 in the form of the invention illustrated in Figures1, 2 and 3.

= Referring now tu Figures 9 and'lo or the dra'wrim portion 82 to whichis secured an end plate 83.

' In rim portion 62 there are provided a plurality of inserts 64aiording a openings 65. v In this form oi.' the invention noacceleration groove is employed as the abrasive is dumped into a recess66 provided in the rotor disc and builds up kon surface 61vwhere it isIdeflected into discharge opening 65 by either a stationary deectormember or a rotatable disc as described in connection with the firstform ofthe invention.

In this form of the invention a cage is employed embodying a coneportion 63 which is secured to a hub portion 1l by a plurality of capscrews 12. Portion 1| is provided with a funnel portion I3 and it issecured to a hollow shaft 14 by means of a key 15 and a'set screw 1B.Shaft 14 is journaled in a support 18 and is provided with an operatinghandle 19. Shaft 14 is adjustably locked in xed position by nut and boltassembly 8i which cooperates with an arcuate slot 82 in support 18',whereby the parts may be locked by tightening the nut and boltiassembly.

Journaled in sleeve 14 is a shaft 53 to which is secured a handle t4 bymeans of a set screw 85. Handle i carries a detent 86 which cooperateswith serrations il formed on`a downward extension 58 of handle l5. Thisdevice is similar to that described in connection with the drst form ofthe invention, the abrasive being admitted in chamber 5d and piling upagainst the inner surface lil of the rotor and being dislodgedordeplurality of discharge fiected through opening 55 by means oi a sta-Aithough wheel 55 may if desired be driven by a- -separate prime mover,it has been found that the tionarily supported deflector either oi thestationary plough or shoe type shown in Figure 5 or vdischarge oi themachine or to compensate for' t wear by loosening the stud and nutassemblies.

In this ioirn of theinvention there is employed a primary deector bladei5 which acts upon the abrasive before blade iid comes into play and asthe initial contact 'is oi greatest magnitude the primary blade takesthe most wear. Accordingly in order to `make blade 5d quickly andeasily' ad justable to compensate for wear it is mounted for guidedsliding movement in a recess in chamber 55 and projects outside chamber55 adjacent the leading edge of blade lili. e

` Pivotally secured to blade-55 by means of a pin 5l is'a connectinglink di, which in turn is connected by means oia crank pin 53 to a disc5d face 5l and blade it will apply a secondary de' ecting actionthereupon. When the outer end of bladev 55 has A.become worn throughcontact wardly into a new position. The parts have been position toeffect the desired discharge of abrar illustrated as new and hence inFigure l lever 84 may be moved step by step through 180 before blade 90is unfit for further service. Also, from time to time blade 88 may beadjusted outwardly to,c0mpensate for4 wear in the manner previouslydescribed.

In Figures 12, 13 and 14, I have shown a com-f bination ofa rimdischarge abrasive throwing wheel used as the feeder for a bladedabrasive throwing wheel.

With continued reference to these figures, a V

rotor H0 mounted on a shaft IH is provided with a plurality of abrasivepropelling blades l I2. The blades terminate short of the axis ofrevolution to define a central spaceand mounted in this space is achamber H3 and it is preferably removable so that it may be taken outand replaced when it has become tooy worn for further service. A

. The abrasive is fed to the interior of member H3 by meansof a feedconduit H5. Journaled in conduit l I5 or in any other suitable manner isa shaft H6, carrying a spider H1 which in turn supports a disc H8. Inthis lforml of the invention abrasive is introduced through chute H5 andpiles up to its angle of repose on the interior of member H3, and at apredetermined point in the rotation of the parts disc H9 defiects alayer of abrasive 'over the edge |2| of member H3 onto the inner ends orheels of the throwing blades. In view of the fact that the direction ofdischarge of the abrasive from member H3 is substantially tangential theabrasive is picked up by the inner ends of the blades with negligibleimpact.

may be controlled in a manner similar to that effected in the wheelspreviously described, name- 1y,` byadjusting angularly the point atwhich` the deector cooperates with the abrasive lying on the innersurface of member H3. Accordingly it is only necessary to adjust. spout,H5 and shaft H6 to locate disc H9 in the proper sive.

Although I have shown member H8 as being driven @synchronously with therotor and feeding the abrasive over the inner ends of the blades, it maybe independently driven and feed the abrasive over the side edges of theblades without departing from the spirit of my invention. Also, I haveillustrated certain parts of the apparatus asbeing integrally formedwith the rotor. but it is tobe understood that if desired separatereplaceable wear elements may be provided.

In all of the forms of the invention ,the abrasive is deposited on ltheinner surface of the rotor and lbuilds up to its angle of repose andtherefore the deector need apply but force enough to cause the abrasiveto move to the discharge point. Therefore, the wear on the deflector isminimized.

The invention may be embodied in other specie forms without departingfrom the spirit or essential ,characteristics thereof. The presentembodiment is therefore to be considered in-all r respects asillustrative and not restrictive, the

scope of the invention being indicated by theV claims are thereforeintended to be embraced therein.

What is claim-:d and desired to be secured by United States'LettersPatent is:

4l. In an abrading apparatus, a structure mounted for rotation athighspeed, said structure providing a. generally annular surface facingtoward 'the'axis of rotation of said structure, means for depositingabrasive upon said surface, and discharge means for dislodging thedeposited abrasive from said surface at a predetermined point in therotation of said structure for projecting said abrasive at an abradingvelocity.

2. The abrading apparatus set forth in claim l, wherein said dischargemeans comprises a stationarily supported device for directly engagingthe deposited abrasive and imparting an axial movement thereto.

3. The abrading apparatus set forth in claim 1, wherein said dischargemeans comprises a stationarily supported device mounted adjacent saidstructure and cooperating with said deposited abrasive, said devicebeing lmovable into a plurality of angular positions with respect to theaxis of saidl structure, whereby the direction of the discharge ofabrasive from said structure may be varied at will.

4. In an abrading apparatus, a structure -mounted for rotation at highspeed, said struc- 5. The abrading apparatus set forth in claim 4,

wherein said discharge means comprises an inclined deflector bladestationarily supported adjacent said structure and operable to engageand deflect said deposited abrasive axially over said one edge of saidsurface.

6. The abrading apparatus set forth in claim 4, wherein said dischargemeans comprises a rotatable member disposed adjacent said structure andoperable to directly engage said deposited abrasive. 1 Y

A'7. In an abrading apparatus, a structure mounted for rotation at highspeed and comprising a hollow member, means for depositing abrasive uponthe inner surface of said member while the latter is rotating andabrasive discharge means for engaging and deiiecting said abrasive overone end of said member while the same is rotating for discharging saidabrasive at an abrading velocity.

- 8. The abrading apparatus set forth in claim '7, wherein said firstnamed means is operable to deposit abrasive upon said member at a pointsufficiently remote from said one end of said member so that saidabrasive will build up to its angle of repose adjacent to but short ofsaid one end `of said member, whereby said abrasive will be dischargedfrom said member only when it is engaged bysaid abrasive dischargemeans.

9. An abrading apparatus comprising a structure mounted for. rotation athigh speed, said structure embodying a hollow lmember rotatable withsaid structure with its axes coincident to theA axis of rotation of saidstructure, said member having a plurality of discharge openings providedtherein disposed in the same general plane of revolution, means fordepositing abrasive upon Y rotating and allowing said abrasive to attainthe 'dil dll

9,116,153 the inner surface -of said member ina region spaced vfrom saiddischarge openings. and means located within said member for engagingthe layer of abrasive deposited within said member and moving it axiallyto said discharge'openings.

10. In Van abrading apparatus, a structure mounted for rotation at highspeed, saidstructure providing an annular inwardly facing abrasivesupporting surface terminating at one end in an abrasive discharge edge.means for depositing abrasive upon said surface while said structure isfull peripheral speed of said inner surface, said abrasive beingdeposited upon said inner surface at a point spaced from said dischargeedge and adapted to build up thereon to its angle 'of repose withoutspilling over said discharge edge, and a rotatable disc mounted adjacentsaid structure fordeilecting said deposited abrasive over said dischargeedge and discharging it at an abrad- .ing velocity.

A11. The abrading apparatus set forth in claim 10, wherein saidVstructure is provided with an abrasive acceleration groove adjacent saidannular surface which is adapted to accumulate a body of abrasive whensaid structure is rotating.

12. 'I'he abrading apparatus set forth in claimv l0, wherein saidstructure is provided with means for accelerating the abrasive in stagesbefore it is depositetl upon said annular surface, whereby said abrasivepromptly attains the full peripheral speed of said structure uponcontact therewith.

13. In an abrading apparatus, a structure mounted for rotation at highspeed and having a plurality of abrasive propelling blades providedthereon, and means mounted adjacent the center of rotation of saidstructure for feeding a stream of abrasive over the edges of said bladesfor causing the abrasive to be picked up and-discharged by said bladesin a predetermined direction, said means comprising 4a rotatable elementproviding an inwardly facing surface; means for feeding abrasive to saidsurface; and means for dedecting the abrasive accumulated on saidsurface into the path of rotation of said abrasive propelling blades.

1d. lin an abradingapparatus, arotor having a plurality of abrasivepropelling blades terminating short of the axis of rotation to define acentral abrasive admitting space, abrasive feeding means mounted in saidspace and rotating synchronously with said rotor providing an inwardlyfacing abrasive supporting surface, said surface having a discharge edgedisposed between the inner ends of said blades, means for depositingabrasive upon saidsurface, and abrasive deflecting means for deectingthe abrasive deposited on said surface over said discharge edge into'the path of rotation-of the inner ends of said blades.

l5. The abrading apparatus set forth in claim 14, wherein said abrasivedeecting means comprises a disc .disposed within said abrasive feedingmeans and mounted for rotation about an` 'means for moving saiddeposited abrasive axially so as to discharge it from one edge of saidsurface when said abrasive attains a predetermined position in therotation of said structure, said discharge means comprising a primarydeflecting element and a secondary denecting element for en'glng thedeposited abrasive, said primary deiiecting element having means foradjusting it toward and away from said generally cylindrical 17. In anabrading apparatus, a head structure mounted forV rotation and providinga generally annular surface facing toward lthe axis of rotation of saidhead structure, means for depositing abrasive upon said surface. andcontrol means forv causing the deposited abrasive to discharge from'b rsaid surface at a predetermined pointin there-ff tation of said head atan abrading velocity.;

18. The apparatus set'forth in 17, wherej' in said control meanscomprises a tating about an axis inclined to theaxisoffsaid headstructure and ico-operatingwiththe sive deposited on said annularsurface.'u v 19.v In an abrading apparatus. 'a-fhead structure mountedfor rotation and havingan [annular abrasive accelerating groove facingtoward. the

axis of rotation of said head, means for depositingabrasive 'in saidgroove, said head structure also providing a generally annular, inwardlyfacing surface adjacent said groove and adapted to receive abrasiveoverflowing from said groove and control means for causing the dischargeof abra-4 sive from said annular surface at a predetermined point in therotation of said head structure.

2i). In anabrading apparatus, Aa rotor mounted for rotation at highspeed and having a plurality of abrasive propelling Ablades providedthereon; a generally cylindrical rotating feed chamber mounted adjacent,the axis of rotation of said rotor; means for-feeding abrasive to saidfeed chamber for causing vit to centrifugally build up to its angle ofrepose on the inner surface of said feed chamber; and means fordenecting the accumulated abrasive from said feed chamber intothe pathof said abrasive propelling blades at a predetermined point in therotation of said rotor', for causing the abrasive to be picked up anddischarged by said blades rection. I

dl. lin an abradlng apparatus, a rotor mounted for rotation at highspeed and having a plurality of abrasive propelling vblades providedthereon, said blades terminating short of the anis of rotation of saidrotor to denne a central space; a generally cylindrical feed chambersecured 'to in a predetermined disaid rotor, and projecting into saidcentral space, said feed chamber terminating at one end in a' dischargeedge located adjacent the inner ends of said blades, means for feedingabrasive to said feed chamber, whereby it centrifugally accumulates onthe inner wall thereof, and `means for' /dehecting the accumulatedabrasive from said their side edges contiguoim to, one face thereof,.

and said feed chamber is secured to said structure with its dischargeedge located between said structure and a plane normal to the axis ofrotation of said rotor and disposed midway between the side comes ofsaid abrasive propelling blades.

23. The abrading apparatus dedned in claim 2l.,

wherein the diameter of said feed chamber is approximately equal to thelength of said blades.

24. In an abrading apparatus, a structure whereby the point in therotation of said struc ture at which the abrasive is deected into thepath ofrctation of said blades may be selectively varied.

25. In an abrading apparatus. a rotor having a`plurality of` abrasivepropelling yblades provided thereon; arotatable element mounted adjacentthe axis of rotation of said rotor and providing an inwardly facingabrasive accumulating surface; feeding means i'or supplying abrasive tosaid surface;- and a rotatable disc for deilecting the abrasiveaccumulated on said surface into the path of rotation of said abrasivepropelling blades at a predetermined point in the rotation of said rotorfor causing the abrasive to be picked up and discharged by said bladesin a predetermined direction, said disc having a central opening, saidfeeding means being operable to discharge abrasive into said rotatableelement through the central openingof said disc.

26. In anv abrading apparatus, a rotor having a plurality of abrasivepropelling blades provided thereon, said blades terminating short of theaxis of rotation of said rotor to define a central space; said rotorhaving in said central space an inwardly facing abrasive accumulatingannular ledge rotatable synchronously with said rotor and having adischarge edge located adjacent the path of rotation of the inner endsof said blades, and between the planes of rotation defined by the sideedges of said blades; means for depositi ing abrasive upon said ledge,and means for delfleeting the accumulated abrasive from said ledge overthe discharge edge thereof and onto the inner ends of said blades at apredetermined point in the rotation of said rotor, for causing saidabrasive to be discharged in a predetermined direction from said rotor.

WALTER L. man.

